Final answer:
Frederick's army faced challenges such as severe snowstorms in the Alps, extreme cold, and supply shortages, all of which led to operational difficulties, increased desertions, and hampered military effectiveness.
Step-by-step explanation:
Frederick's army faced numerous challenges during the journey due to several reasons. Some of these challenges included hostile environments such as severe snowstorms in the Alps, which made it difficult for soldiers to fight at high altitudes and often led to frostbite, avalanches, and casualties. Moreover, troops encountered issues with supply shortages, as advancing armies required significant amounts of supplies, but the logistics couldn't keep up, leading to shortages of food, clean water, and necessary equipment. Weather also played a detrimental role, especially for German forces during World War II, where both mud and extreme cold conditions caused suffering among the troops, who were not properly equipped for winter warfare, resulting in immobile machinery and high rates of horse fatalities. These factors collectively demoralized the troops, increased desertion rates, and ultimately hindered military operations.